The D250S DUAL charger obtains its energy from DC sources such as alternators, solar panels or wind power and optimises this power to meet the changing requirements of different battery banks. The D250S DUAL automatically selects the best connected Dc energy source (of2) for the purpose and switches between these energy sources to achieve high efficiency multi-stage charging vehicles that do not have access to grid power supplies. Charging automatically starts as soon as Dc Energy is provided to the charger, for example, from alternators when a vehicle is started or from solar panels when connected.The D250S DUAL ensures that your batteries are always in good condition, quick charging and long battery lifetimes.